I think “Overwhelmed” here means overwhelmed by too much to do. I first read it as “ overwhelmed by emotion”, so none of the recommendations made sense to me.
When I’m overwhelmed by emotion and I’m in a situation where I can’t just let myself feel the emotion until it passes, I find that several seconds of focusing my attention on my immediate physical environment – my breathing, the temperature, the sounds around me, the weight of my feet on the floor, etc. – will be very helpful in calming myself and getting into a headspace where I can be functional.
The hard part is remembering to make time later for processing out the unfinished feelings.